Light conversion in nonlinear monomode optical fibers

A complementary analysis of the four-wave mixing phenomenon in monomode optical fibers is undertaken. Its central aspect is the interdependence between the amplitudes and the relative phase of the four waves. An expression for the spontaneous emission in terms of the pump power is derived. Investigating the pump depletion it is shown that for short fibers a certain degree of total phase mismatch can be advantageous to the amplification of weak Stokes and anti-Stokes signals. Also the optimal fiber length depends on the initial relative phase.